Why You Should Actually Pay Attention To Sunscreen Expiration Dates

We've been warned time and time again about the risks of holding onto mascara past the six-month mark. But even faced with the threat of growing bacteria, we still find ourselves applying from tubes that have been kicking around our makeup bags for a year or more. (Hey, it hasn't killed us yet.) Admittedly, it's not the most hygienic habit, but it does appeal to our inner cheapskate that doesn't love the idea of spending $30 to replace our Diorshow every few months when the tube is still half-full.

So when we happened upon a beautifully formulated, very expensive, and just-this-side-of-expired tube of La Prairie Cellular Swiss UV Protection Veil Sunscreen Broad Spectrum SPF 50 at the bottom of last summer's weekender bag, we began to wonder if we could play fast and loose with its shelf life, too. Can that looming deadline printed on every sunscreen sold in the US also be taken as a "helpful suggestion" — or is it as non-negotiable an expiration date as the one on a carton of milk?

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For answers, we turned to Jessica Wu, a Los Angeles-based dermatologist and author of Feed Your Face. Dr. Wu told us what we needed (but didn’t want to) hear: "Expired sunscreen may no longer protect you from UV rays, and it may also be less water-resistant than what it says on the label," she says. And that’s just the start: “Over time, ingredients can break down and cause skin irritation and allergic reactions,” Dr. Wu says. “Expired sunscreens can also start to grow mold or bacteria, leading to skin infections.” If the whole purpose of wearing sunscreen is to protect skin against photoaging and cancerous UV rays, then Dr. Wu just shut down any reason to ever bother with an expired batch.

But say an expiration date has rubbed off of a sunscreen bottle (which, given the condition of our beach bags, is entirely possible): How are we to tell whether the stuff inside is still good? In these cases, Dr. Wu suggests paying particular attention to consistency and color. “Mineral sunscreens that have been sitting in your bathroom for a long time can separate,” she says. “If a runny liquid is dispersed from what was at one time a creamy formulation, then zinc oxide or titanium dioxide particles have likely sunken to the bottom of the tube — and it should be tossed. Meanwhile, chemical sunscreens that have gone bad are more likely to change color and turn yellow, or smell odd."

Though Dr. Wu suggests erring on the side of caution when it comes to using sun protection that, well, no longer protects you from the sun, she does allow for a little wiggle room. “Generally, mineral sunscreen ingredients tend to break down more slowly than active chemical ingredients, so they’re slower to expire,” she says. “Since sunscreen loses efficacy gradually, not overnight, you're probably fine to use it for another few months after it’s marked to expire.” Past that, it’s best to ditch the old bottle and bring in new. Her absolute cut-off point for usage? “I wouldn’t recommend using sunscreen that’s more than six months past its expiration date,” she says — which means it’s officially time to say goodbye to our long-lost luxe formula and hello to a new resolution: Come the end of swim season this year, we won’t have a drop of leftover sunscreen to spare.